JavaScript构建字符串金字塔

//从侧面看金字塔
	function watchPyramidFromTheSide(characters) {
	var str = "";
	for(var i=characters.length-1;i>=0;i--){
	for(var j=0;j<i;j++){
	str += " ";
	}
	var num = 2 * characters.length - 1 - j * 2;
	for(j=0;j<num;j++){
	str += characters.charAt(i);
	}
	for(j=0;j<i;j++){
	str += " ";
	}
	if(i>0){
	str += "\n";
	}
	}
	return str;
	}
	
	//从上方看金字塔
	function watchPyramidFromAbove(characters) {
	var matrix = [];
	var str = "";
	//边最长为
	var sideLongest = characters.length * 2 - 1;
	for(var i=0;i<characters.length;i++){
	var chr = characters.charAt(i);
	for(var j=i;j<sideLongest-i;j++){
	if(!matrix[j]){
	matrix[j] = new Array(sideLongest);
	}
	for(var k=i;k<sideLongest-i;k++){
	matrix[j][k] = chr;
	}
	}
	}
	//组合字符串
	for(i=0;i<matrix.length;i++){
	str += matrix[i].join("");
	if(i<matrix.length-1){
	str += "\n";
	}
	}
	return str;
	}
	
	//能看到的金字塔字符数
	function countVisibleCharactersOfThePyramid(characters) {
	return Math.pow(characters.length * 2 - 1,2);
	}
	
	//金字塔总字符数
	function countAllCharactersOfThePyramid(characters) {
	var len = characters.length;
	var count = 0;
	while(len >= 1){
	count += Math.pow(2 * len - 1,2);
	len--;
	}
	return count;
	}